胆碱类低共熔溶剂(Ch-DES)定量构效关系及其辅助微藻油脂提取机理研究

Microalgae is a raw material of biofuel of great potential, however the microalgae cells have rigid cell walls, lipids are binded with cytoplasmic inside the cell, which is unfavorable to be extracted. Choline-based eutectic solvents(Ch-DES),synthesized by the applicant, could be used to improve microalgae total lipid yield significantly, and Ch-DES have many advantages, such as easy production, non volatile, and other advantages which toxic organic solvents can not be comparable, but the quantitative structure/property relationship of Ch-DES physicochemical properties and the chemical mechanisms of lipid extraction assisted by Ch-DES is not clear. The project will fous on building of mathematical model among physicochemical properties and the influence parameters based on mutiple stepwise regression method and explanation of structure/property relationship of lipid extraction assisted by Ch-DES and establishment of mass transfer kinetics model of the lipid extraction process aided by Ch-DES. Firstly, effect of hydrogen bond donor structure on the physicochemical properties of Ch-DES will be studied. Secondly, chemical mechanisms and structure-property relationship of Ch-DES in assistance of lipid extraction will be clarified, and finally, kinetics characteristics of mass transfer of microalgae lipid extraction will be investigated and kinetics model of mass transfer of microalgae lipid extraction assisted by Ch-DES will be established. The structure/property relationship of Ch-DES and internal mechanisms of lipid extration from microalgae by Ch-DES can be revealed through the research.

微藻是一种非常有潜力的生物燃料生产原料，然而由于微藻细胞具有坚硬的细胞壁，油脂与细胞质结合于细胞内，不利于微藻油脂的提取。申请人前期合成的胆碱类低共熔溶剂(Ch-DES)能辅助显著提高微藻总脂得率，且具有易生产、无挥发、无毒性等有机溶剂不可比拟的优点，但Ch-DES理化性质的定量构效关系及其辅助提取微藻油脂的化学机制尚未清楚。本项目基于多元逐步回归法，构建Ch-DES理化性质与其影响参数的数学模型，解析Ch-DES提高微藻总脂得率的构效关系和构建微藻油脂提取过程传质动力学模型。首先研究氢键供体分子结构对Ch-DES理化性质的影响，其次阐明Ch-DES辅助提取微藻油脂的化学机理和构效关系，最后考察Ch-DES条件下微藻油脂提取的传质动力学特征，建立适用于Ch-DES辅助微藻油脂提取的传质动力学模型。通过本项目的研究揭示Ch-DES理化性质的构效关系及Ch-DES辅助微藻油脂提取的内在机理。

微藻油脂提取是微藻生物柴油生产的第一步，利用低共熔溶剂(DES)辅助微藻油脂提取是有效可行的。(1)项目组探讨了胆碱类低共熔溶剂（Ch-DES）理化性质的定量构效关系及其辅助提取微藻油脂的化学机制，制备了系列DES，包括氯化胆碱—醇、氯化胆碱—羧酸、氯化胆碱—酰胺等。对影响DES粘度、密度、热稳定性等物化性质进行探讨发现：氯化胆碱-醇低共熔溶剂（Ch-Gly）的粘度与温度的关系更符合Arrhenius方程，水的加入显著地影响低共熔溶剂的粘度；在相同温度下，随着甘油与氯化胆碱的摩尔比逐渐减小，Ch-Gly的粘度也逐渐降低；Ch-Gly的密度随着甘油的摩尔比增加也增大，其范围在1.1821-1.2100g/cm3之间，不同氯化胆碱与甘油摩尔比的Ch-Gly分解温度均在160℃以上。(2)油脂提取实验发现：三种DES预处理的小球藻（奶牛场废水大规模培养）油脂提取率高达80.90 %、75.25 %和66.92 %。通过扫描电镜观测，小球藻细胞被一定程度地破坏为不规则形状。这由于DES分子与微藻细胞壁中的纤维素、半纤维素分子中的羟基形成氢键降低了微藻细胞壁中的大分子（如纤维素和半纤维）分子间的氢键作用。(3)根据Fick第二定律，由于当氯化胆碱-乙二酸低共熔溶剂加入量为0.08g时，中性油脂提取率98.08%，此条件下一级动力学模型为实验值与理论值的标准方差均小于0.05。通过上述讨论，系统地阐述Ch-DES的理化性质及辅助微藻油脂提取的机理，为微藻生物柴油工业大规模发展提供理论基础。截止到项目执行期，第一标注发表论文7篇，其中SCI论文6篇，EI论文1篇；第二标注发表SCI论文2篇；著作一部。达到计划书中的规定指标。